1. Field of the Invention
The present invention relates to a color image processing apparatus that executes an image process for limited-color print in color document printing.
2. Description of the Related Art
In the prior art, in color document printing, there are full-color printing in which original colors are output with fidelity and limited-color printing in which the number of colors is reduced and printing is effected. The limited-color printing is effective means capable of saving color materials and reducing a printing cost.
A commonly used method is red/black 2-color printing. In the red/black 2-color printing, the colors to be used are limited to red and black, as the term of this method indicates. In another color-reducing method, limited colors to be used are selected oh the basis of the color state of an original color document (the kinds of colors appearing on the document).
There has also been proposed a method in which the color state of each page of an original color document is detected in association with multi-page continuous printing, and the selection of limited colors is changed.
It is important to reduce a printing cost and to enhance the ease in reading/understanding, in particular, in limited-color print for business documents.
For example, in the case of a color document including both a photo region and a character region, proper color assignment has to be done to the respective regions. If uniform color assignment is done, it would be likely that the photo region becomes difficult to view, or color characters that to be emphasized in the character region may be assigned a color that differs from the intended color at the time when the original document is created. On the other hand, there may be a case in which it is effective, in terms of ease in understanding, to intentionally use a color that differs from the color on the original color document.
In the conventional limited-color printing technique, in particular, in connection with the above-described case, it is difficult to assign different colors to a photo region and a character region, or to flexibly assign colors in accordance with the color state.